BPM Sync vs Beat Sync - What's the difference ?

I can see that...

BEAT SYNC: When BEAT SYNC is turned on, the BPM and beat position of the track playing on the deck is automatically synchronized with those on the deck set as the MASTER. 

BPM SYNC: When BPM SYNC is turned on, the BPM of the track being played on that deck is automatically synchronized with those on the deck set as the MASTER.

Think of it this way... it's quantize for you to start playback without having quantize enabled for the other functions.

bpm sync: the bpm will be matched without grids

beat sync: bpm and grids will be matched

thanks.

how does it match without grids ?

Just the tempo is set the same - they don't align to the phrasing of the grid.

ok, but my question is: I always need to analyze the tracks if I use the bpm sync ?

what's the big difference when I mix with Sync using the "bpm" option instead of "beat" ? I can not understand

which one is better to use ?

thanks

Without analysis rekordbox can't even apply a BPM sync because it doesn't know the tempo of the song - full stop.

If you have BEAT sync enabled, it makes it easier to snap the two songs together when pressing sync whereas the BPM sync just makes the two tracks at the same tempo.

what i don't understand is why should I use the bpm sync if the beat sync works better and with grid

Some people just want to match the pitch, not the grid.

ok. but how does it affect the tempo during the mix ?

sorry, but i'm not understanding the difference and how they work

None; they stay the same.

One syncs the tempo, the other syncs the tempo AND the grid.

ok. I don't want to look boring, but I really don't understand the difference between "tempo" and "grid".

could you explain how does rekordbox set the bpm and why there are these 2 options ?

thanks